Thermally-operated control device



Jan. 1925. 1,524,571

T. A. REID THERMALLY OPERATED CONTROL DEVICE Filed June 1921 INVENTOR 7' f1 (gems/4. P910 ATTORNEY Patented Jan. 27, 1925 UNITED STATES PATENT OFFICE.

THOMAS A. REID, F PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTBICfi MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

V THEBMALLY-OPERATED CONTROL DEVICE.

Application filed June 3,

To all whom it may concern:

Be it known that I, THOMAS A. Ram, a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Thermally-Operated Control Devices, of which the following is a specification.

My invention relates to control devices and particularly to thermally-operated controllin devices.

1511c object of my invention is to provide means for opening a circuit when t e temperature in a portion of the circuit attains or exceeds a predetermined value.

Another object of my invention is to provide means whereby a device of the aboveindicated character may be employed to con- .trol or regulate the temperature of an electrically heated furnace or similar heat-storage device.

A further object of m invention is to rovideIa device of the above-indicated 0 aractor that shall comprise parts which shall be self-resetting for a subsequent operation. In racticing my invention, I provide a rod 0? expanslble material for controlling a band-brake that is associated with a ratchet wheel which is employed to maina switch in its closed position. When.

the expansible member is heated to a prede-- degree, the band-'blmke is sulficiently loosened to permit the ratchet wheel to be moved to release the switch normally restrained thereby.

Figure 1 of the accompanying drawings is a view, partially in diagram and partially in elevatlon, of an electrical circuit and a device contained therein embodying my invention.

Fig. 2 is a plan view of the rod illustratin the adjustable feature-thereof. I

Fig. 3 is a plan view illustrating the arrangement of the band-brake and the ratchet wheel. g

Fig. 4 is a view, partially in elevation and partially in section, illustratin the disposition of the device shown in ig. 1 in an electric furnace, and

Fig. 5 is a. plan view of the controlling device, illustrating the disposition of the various parts thereof.

. Referring to Fig. 1, a motor 1 is supphed with energy from a source 2 of electromotive force through a switch 3, the operation of 1921. Serial 110. 474,808.

which is controlled by a controlling device 4. The device 4 comprises a rod 5 of expansible material, a heating winding 6 disposed therearound, a band-brake 7 that is disposed on a shaft 8 and a ratchet wheel 9 that is also disposed on the shaft 8. The

band-brake 7 comprises a drum 10 and a band 11, one end of which is secured to the structure 12 and the other end of which is secured to the rod 5.

, The rod 5 is provided with a spring 13 that co-operates with a bracing member 14 to maintain the rod in such position as to normally tension the band 11 to prevent movement of the drum 10. While the temperature of the rod 5 is less than a predetermined value, the switch 3 is maintained in its closed position by the ratchet wheel 9. lVhen the temperature of the rod 5 attains a predetermined value, expansion corresponding to the permissible rise in temperature is permitted and arranged for by means of an adjusting bolt 15.

The screw 15 co-operates with a slot 16 in the rodand a stationary slotted member 17 to determine the degree to which the rod 5 may be expanded before operating the brake 7 to permit the release of the switch 3.

Referring to Fi ,4 and 5, similar elements are employe as shown in the previous figures, and the expansion portion of the expansible rod 5- is disposed within the furnace or other heat-storage device '18 the temperature of which is to be regulated and controlled between predetermined values. Adjustable means 19 are rovided to adjust the expansion of the rod correspondin to a predetermined temperature at which t is desired to disconnect the heat resistors from the energizing circuit.

When the rod 5 ex ands an amount corresponding to a pre etermined value, the movable end thereof butts against the bolt 15 in Fig. 1 or against a stationary portion 20 of the structure in Fig.4, and, upon further increase of temperature andv corresponding expansion of the rod, the spring 13 is compressed and the band 11 loosened to permit the switch 3. to be opened by a spring 21.

In the device shown in Fig. 1, the degree of ex ansion, corres onding to a redetermin temperature t at may be e acted in btlgiarod 5, is adjusted by the adjusting My invention is not limited to the specific structure that is illustrated, since modifications may be made therein within the spirit and scope of the invention, as set forth in the appended claims.

I claim as my invention:

1. The combination with a furnace, a heater therefor, a source of energy for the heaterand an interlupter disposed between the source ofenergy and the heater, of a rotatable shaft, a ratchet Wheel mounted there'- on for normally, maintaining the interrupter closed, a band-brake also mounted on the shaft to control the movement thereof and means responsive to the temperature of the furnace for controlling the band-brake.

2. The combination with a furnace, a heater element therefor and a source of energy for the heater element, of means for controlling the admission of energy to the furnace heater element comprising a movable member, a spring, friction means controlled thereby for normally restraining the movable member and a thermal element responsive to the furnace temperature for 0011-,

t1'0lll1 11 the effectiveness of the spring.

e combination with a device to be heated, a heater element therefor and a source of energy for the heater element, of means for controlling the admission of energy to the heater element comprising an energy-admitting device, a member for controlling movement thereof, a spring restraint for said member and thermally responsive means for controlling the effectiveness of the spring restraint.

4. The combination with a device to be heated, a heater element therefor and a source of energy for the heater element, of means ,for cont-rolling the admission of energy to the heater element comprising an energy-admitting device, a movable member for controlling said energy-admitting device, means comprising a spring element for controllin the movable. member, andvmeans for contro ing the effectiveness of the spring element according to the temperature of the device to be heated.

5. The combination with a device to be heated, a heater element therefor and a source of energy for-.the heater element, of

means for controlling the admission of energy to the heater element comprising an energy-admitting'device, a movable member for controlling said energyradmitting device,

means comprising a spring element for controlling the movable member and means respon'sive to the temperature of the device to be heated for controlling the effectiveness of the spring element.

In testimony whereof, I have hereunto subscribed my name this 14th day of May 1921.

THOMAS A. REID. 

